پاليواكولوژي سازند جيرود در برش چينه‌شناسي گرمابدر، شمال‌شرق تهران

Palaeoecology of the Geirud Formation at the Garmabdar Stratigraphic section northeast Tehran

The Upper Devonian strata of Geirud Formation consist primarily of conglomerates, quartzites, sandstones, siltstones, shales carbonates and are widely distributed in the central Alborz Mountains. Diverse and variously preserved fauna including crustaceans, fish, goniatites, brachiopods in association with land-derived mega- and microfossils (terrestrial palynomorphs) are present in the Geirud Formation at Garmabdar, northeast Tehran. Acritarchs (sensu lato) are diverse and more abundant than spores. The marine palynomorphs such as prasinophyte phycomata, acritarchs, sco-lecodonts, and chitinozoans together with the associated terrestrial elements show an open marine, near shore depositional setting for the Geirud Formation deposits at the studied section; this generally corroborates the available faunal evidence. The associated megflora is poorly diversified and indifferently preserved and are identifiable only at supra-generic level. Geminospora lemurata is quantitatively one of the most important species, being distributed throughout the palyniferous section. It is inferred that the contemporaneous coastal vegetation was relatively diverse, and is most likely dominated by fern allies (including Rhyniopsida, Lycophyta, and Equisetopsida) and archaeopterid progymno sperms.